Odontoid process inclination in normal adults and in an adult population with Chiari malformation Type I.

OBJECT: Posterior odontoid process inclination has been demonstrated as a factor associated with Chiari malformation Type I (CM-I) in the pediatric population; however, no studies to date have examined this measurement in the adult CM-I population. The purpose of this study was to evaluate craniocervical junction (CCJ) measurements in adult CM-I versus a control group. METHODS: The odontoid retroflexion, odontoid retroversion, odontoid height, posterior basion to C-2 line measured to the dural margin (pB-C2 line), posterior basion to C-2 line measured to the dorsal odontoid cortical margin (pB-C2* line), and clivus-canal angle measurements were retrospectively analyzed in adult patients with CM-I using MRI. These measurements were compared with normative values established from CT scans of the cervical spine in adults without CM-I. RESULTS: A statistically significant difference was found between 55 adults with CM-I and 150 sex-matched controls (125 used for analysis) in the mean clivus-canal angle and the mean pB-C2 line. CONCLUSIONS: These data suggest that there are sex-specific differences with respect to measurements at the CCJ between men and women, with women showing a more posteriorly inclined odontoid process. There were also differences between the CM-I and control groups: a more acute clivus-canal angle was associated with CM-I in the adult population. These CCJ findings could have an influence on presurgical planning.

Parotid epithelial-myoepithelial carcinoma: an unexpected intraoperative finding.

We present a case of a 72-year-old man with a parotid mass which was initially diagnosed as a pleomorphic adenoma. Intraoperatively, the tumour was found to be invading the facial nerve. It was later found to be an epithelial-myoepithelial carcinoma, a rare salivary gland tumour. Despite invasion of the facial nerve, function of the nerve remained intact.

Central nervous system and head and neck imaging findings of MYC/BCL2 "double hit" B cell lymphoma.

MYC/BCL2 double hit lymphoma (DHL) is a rare, recently recognised and highly aggressive subtype of non-Hodgkin lymphoma, with an affinity to involve the central nervous system and the head and neck either at initial presentation or during relapse. We present a case of 43-year-old woman with MYC/BCL2 DHL relapse in the nasopharynx with extensive spread to the neck, skull base, and the central nervous system. To our knowledge, this is the first reported case in the literature describing the MRI and CT scan findings and the profound pattern of disease involvement of this rare neoplasm.

Estimation of odontoid process posterior inclination, odontoid height, and pB-C2 line in the adult population.

OBJECT: Posterior odontoid process inclination has been associated with Chiari malformation Type I in the pediatric population. There are varying reports to support a reliable range of odontoid inclination angles in control adults. The purpose of this study is to estimate the normal measurements in adults for odontoid retroflexion, retroversion, height, and the pB-C2 line (a line drawn through the odontoid tip from the ventral dura perpendicular to a second line from drawn the basion to the inferoposterior aspect of C-2 vertebral body) to establish a normative reference in this population. METHODS: After obtaining institutional review board approval, the authors performed a retrospective analysis of non-contrast enhanced cervical spine CT scans obtained in 150 consecutive control adults. Three neuroradiologists measured odontoid retroflexion, odontoid retroversion, odontoid height, and the pB-C2 line. The cohort was divided into sex and two age groups. Comparisons of the means with unpaired 2-tailed t-test were performed. RESULTS: A total of 125 subjects met the inclusion criteria; 80 were men and 45 were women (mean age 52 years, range 18-89 years). The odontoid retroflexion angle ranged from 70° to 89° (mean 79.3° ± 4.9°), and the odontoid retroversion angle ranged from 57° to 87° (mean 71.9° ± 5.3°). The range and mean of odontoid height were 17-27 mm and 22 ± 1.8 mm, respectively. The mean pB-C2 line was 6.5 ± 2.1 mm with a range of 0-11.2 mm. The results were also compared with previously published pediatric data. CONCLUSIONS: The current study demonstrates that the odontoid process in adults is anatomically different from that in children: it is longer, more posteriorly inclined, and has a greater pB-C2 line. Therefore, utilization of these parameters with previously published cutoffs in the pediatric population is not appropriate for surgical planning in adults.

Mastoid findings secondary to posterior fossa dural venous sinus thrombosis.

OBJECTIVE: In the setting of posterior fossa dural venous sinus thrombosis, mastoid findings can potentially be mistaken as the cause rather than a secondary effect. Obstruction of the mastoid venous drainage can lead to transudation of fluid into the mastoid air cells. We hypothesize that a continuum of the mastoid manifestations secondary to dural venous sinus thrombosis can be seen on MRI and that the difference in venous drainage between the mastoid and middle ears can assist with this important imaging differential. MATERIALS AND METHODS: A retrospective review of acute dural venous sinus thrombosis cases and their follow-up imaging were graded as follows: no involvement; grade 1 mucosal congestion; grade 2, film of fluid; or grade 3, complete opacification. Presence of middle ear fluid was also documented. RESULTS: Of 22 posterior fossa dural venous sinus thrombosis cases without clinical infectious mastoiditis, 19 had mastoid findings: eight with grade 1, eight with grade 2, and three with grade 3. Middle ear fluid was seen in only one case. There was a statistically significant association between posterior fossa dural venous sinus thrombosis and mastoid findings (chisquare test (n = 22), p < 0.04). Fifteen of 18 cases with follow-up MRI examinations showed lessening of the mastoid findings with resolving dural venous sinus thrombosis. CONCLUSION: Acute posterior fossa dural venous sinus thrombosis may present with a spectrum of mastoid findings that should not be misdiagnosed as the cause of the thrombosis. This study illustrates that in the absence of clinical findings of mastoiditis, mastoid fluid with a clear middle ear argues that the mastoid changes are the effect of the dural venous sinus thrombosis rather than the cause.